In the U.S. alone, 250,000 spinal fusion operations are performed annually. The typical spinal fusion procedure includes placing harvested bone graft material and/or a bone substitute material into an intervertebral disc space between adjacent vertebrae to facilitate fusion of the vertebrae.
With increasing experience and technical advancements in minimally invasive spine surgery, the surgeon is faced with constraints in his ability to adequately and efficiently deposit bone graft and/or composite bone substitute into the intervertebral disc space. Spinal fusion surgery can be performed through various exposures and corridors (i.e., anterior lumbar interbody fusion, post-lumbar interbody fusion, endoscopic trans-thoracic or lumbar fusion, posterior lateral or retroperitoneal/trans-sous split). Each of these fusion techniques requires manual packing of bone into the intervertebral disc space which is tedious and time consuming.
A limiting constraint for the surgeon is the size of the opening into the intervertebral disc space to be filled. Another constraint is the distance from the spine that needs to be traversed through percutaneous or portal techniques.
In most of the spinal fusion procedures, a plunger-style device is used to inject the bone graft material into the intervertebral space. Due to the nature of some types of bone graft material, it is common for the plunger to become jammed by some of the bone graft particles. Thus, an apparatus for depositing bone graft material that is designed to prevent jamming is desirable.